1. Field of the Invention
The invention, particularly, relates to a card-shaped semiconductor storage device which is suitable when it is used to store data of contents that is distributed through a network and to an operation setting method of such a card-shaped semiconductor storage device.
2. Description of the Related Art
A service to distribute music data by using the Internet has been started. In such a service, a site for distributing the music data is provided on the Internet. When the user selects a desired music piece by accessing the site, the selected music data is transmitted via the Internet and downloaded to a recording medium.
A service to distribute music by using a digital satellite broadcasting has been also proposed. In such a service, the music data for downloading and data of a script language such as MHEG (Multimedia and Hypermedia Information Coding Experts Group), XML (extensible Markup Language), or the like for forming a picture plane for downloading are transmitted as additional data by a music channel together with video data and audio data for providing a music program. The picture plane for downloading is formed by the data of the script language. When an instruction is given by the picture plane, the music data transmitted for downloading is downloaded to the recording medium.
Further, a service to distribute music by using a cellular phone has been proposed. According to such a service, when a line is connected to a predetermined dial number by the cellular phone, the user can receive the distribution of music data. When the user operates the cellular phone, desired music data is transmitted via a network of the cellular phone and downloaded to a recording medium loaded in the cellular phone.
The services to provide the contents such as music data, printed matter, game software, and the like by using various transmitting media such as Internet, digital satellite broadcasting, cellular phone line, and the like as mentioned above are taken into consideration. In such services, the transmitted data is downloaded to the recording medium.
As a recording medium for downloading the data of the contents as mentioned above, it is possible to use a magnetic disk such as floppy disk, hard disk, or the like or an optical disk or magneto-optical disk such as CD-R (CD-Recordable) or MO (Magneto-Optical). However, such a disk-shaped recording medium has a problem on vibration proof since it includes a mechanical portion, it becomes large in size, and it is difficult to carry outside or to easily use it.
To solve such problems, it has been proposed to use a memory card called memory stick as a recording medium for downloading the data of such contents.
The memory stick is a card-shaped nonvolatile semiconductor memory using an NAND type flash memory. The memory stick has an access speed of about 20 MB/sec by using a serial half duplex sync data transfer system instead of a parallel interface using a PCMCIA (Personal Computer Memory Card International Association) interface which has conventionally been widely used. In the memory stick, a high speed access is possible and a memory capacity of up to about 64 MB has been scheduled. The capacity of 64 MB of the memory stick is larger than a memory capacity (1.4 MB) of the existing floppy disk and is regarded to be a capacity large enough to record the data of the contents. Although such a capacity is smaller than a memory capacity (128 MB to 640 MB) of an MD (Mini Disc) or CD-R, the MD or CD-R is large in size because it includes the mechanism portion and is difficult to be easily handled. On the other hand, the memory stick is small, can be easily handled, and is excellent in vibration proof.
For example, in case of downloading music data, such a situation that the user reproduces the downloaded music data by a portable headphone stereophonic apparatus or a car audio apparatus is considered. According to such a using method, the small memory stick having excellent vibration proof is regarded to be a very useful recording medium.
However, in the memory stick, it is a present situation that a CPU is not built in and a security function is incomplete. In case of downloading music data, it is necessary to enhance the security for the purpose of protection of the copyright. Particularly, when the data of those contents is obtained by using the network, there is a method of charging by using electronic money. In the memory stick, since no CPU is built in, such a charging process is difficult.
An IC card has been known as a card in which a CPU has been built. For example, in a cellular phone of a GSM (Group System for Mobile Communications) system in Europe, an IC card called SIM which conforms with ISO7816 is used. Such an IC card is used for storing an authentication, contents of a contract, enciphering algorithm, abbreviated dial numbers, and the like by a cellular phone of the GSM system. An IC card in which a CPU has been built is used in the field of electronic money such as pay television or mondex system. Such an IC card has a high secrecy against a copy and a forgery as compared with that of a memory card.
However, since memory capacities are small and access speeds are low in those IC cards, it is difficult to use them for an application for storing the downloaded contents.
It is, therefore, an object of the invention to provide a card-shaped semiconductor storage device in which the security can be enhanced and a compatibility with an existing memory card can be realized and to provide an operation setting method of such a card-shaped semiconductor storage device.
According to a preferred aspect of the invention, there is provided a card-shaped semiconductor storage device having a construction of a memory card, comprising: a nonvolatile semiconductor memory; data input/output control means for performing an input/output control of data to/from the nonvolatile semiconductor memory; and interface means with an external apparatus, wherein the storage device further has enciphering means for enciphering the data to be stored in the nonvolatile semiconductor memory and control means for controlling the encipherment.
According to another aspect of the invention, there is provided an operation setting method of a card-shaped semiconductor storage device having a construction of a memory card comprising: a nonvolatile semiconductor memory; data input/output control means for performing an input/output control of data to/from the nonvolatile semiconductor memory; and interface means with an external apparatus, wherein the data is enciphered and the enciphered data is stored in the nonvolatile semiconductor memory.
A CPU and an enciphering circuit are provided for the memory card with a construction of a memory stick. The data which is inputted or outputted is enciphered and stored in a flash memory. As command systems for accessing the memory stick, a public command system and a non-public command system are provided. As for file data which is stored in the flash memory, an access limitation, copy guard information, and an encipherment and a personal identification number at the time of access can be selectively set every file data. Processes of those file data are managed by a data file including a hidden data file. An access right is set into the file data and accesses for reading and writing the file data are limited in accordance with the access right. Since the data is enciphered and stored in the flash memory as mentioned above, a security of the stored data is enhanced.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.